Compact, broadband, and efficient LP01 -LP11a mode converter based on cascaded asymmetric Y-junction

Abstract In this paper, a compact and broadband mode converter, which can achieve efficient LP01-LP11a mode conversion, is demonstrated with cascaded asymmetric Y-junction in polymer waveguide. Our typical fabricated converter has a compact footprint of 1.5 mm × 14 µm and shows a mode conversion efficiency larger than ~ 98%, a crosstalk less than ~ −17.5 dB, and an insertion loss lower than ~ 5.8 dB for both x and y polarizations over the C + L band. Our proposed mode converter could find applications in broadband mode-division multiplexing transmission systems.